Watson-Marlow 720UN and 720SN User Manual
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9.2 Do’s and do not’s
Do not
build a pump into a tight location without adequate airflow around the pump.
Do
ensure that when the 720N watertight module is fitted the seals are intact and
properly located. Ensure that the holes for cable glands are properly sealed to main-
tain the IP66 / NEMA 4X rating.
Do not
strap the control and mains power cables together.
Do
keep delivery and suction tubes as short and direct as possible - though ideally
not shorter than 1m - and follow the straightest route. Use bends of large radius: at
least four times the tubing diameter. Ensure that connecting pipework and fittings
are suitably rated to handle the predicted pipeline pressure. Avoid pipe reducers and
lengths of smaller bore tubing than the pumphead section, particularly in pipelines on
the suction side. When pumping viscous fluids use pipe runs with a bore several times
larger than the pump tube. Any valves in the pipeline (not usually needed) must not
restrict the flow. Any valves in the flow line must be open when the pump is running.
Do
ensure that on longer tube runs at least 1m of smooth bore flexible tubing is con-
nected to the inlet and discharge port of the pumphead to help to minimize impulse
losses and pulsation in the pipeline. This is especially important with viscous fluids and
when connecting to rigid pipework.
Do
site the pump at or just below the level of the fluid to be pumped if possible. This
will ensure flooded suction.
Do
keep the pumphead track and all moving parts clean and free from contamina-
tion and debris.
Do
run at slow speed when pumping viscous fluids. Flooded suction will enhance
pumping performance in all cases, particularly for materials of a viscous nature.
Do
recalibrate after changing pump tubes, fluid, or any connecting pipework. It is
also recommended that the pump is recalibrated periodically to maintain accuracy.
IP66 / NEMA 4X
models may be hosed down, but should not be immersed. Protect
from prolonged UV exposure.
When using Marprene or Bioprene
continuous tubing, do re-tension the tube after
the first 30 minutes of running.
Tube selection
: The chemical compatibility lists published in Watson-Marlow publi-
cations are guides. If in doubt about the compatibility of a tube material and the duty
fluid, request a Watson-Marlow tube sample card for immersion trials.
Do not
run the pump with no tube or element fitted to the pumphead. If the direc-
tion is changed, the rotor will continue turning as it tries to reverse and the software
will flag an error condition.
